Biodegradation of diuron by an endophytic fungus Neurospora intermedia DP8-1 isolated from sugarcane and its potential for remediating diuron-contaminated soils

RESEARCH ARTICLE Biodegradation of diuron by an endophytic fungus Neurospora intermedia DP8-1 isolated from sugarcane and its potential for remediating diuron-contaminated soils Yanhui Wang1,2,3☯, Honghong Li1,3☯, Guojun Feng1,3, Liangwei Du4‡*, Dongqiang Zeng1,3‡* a1111111111 a1111111111 a1111111111 a1111111111 a1111111111 1 Institute of Pesticide and Environmental Toxicology, Guangxi University, Nanning, PR China, 2 Guangxi Key Laboratory of Biology for Crop Diseases and Insect Pests, Plant Protection Research Institute, Guangxi Academy of Agricultural Sciences, Nanning, PR China, 3 Guangxi Key Laboratory of Agric-Environment and Agric-Products Safety, Guangxi University, Nanning, PR China, 4 College of Chemistry and Chemical Engineering, Guangxi University, Nanning, PR China ☯ These authors contributed equally to this work. ‡ These authors also contributed equally to this work. * (LD); (DZ) OPEN ACCESS Citation: Wang Y, Li H, Feng G, Du L, Zeng D (2017) Biodegradation of diuron by an endophytic fungus Neurospora intermedia DP8-1 isolated from sugarcane and its potential for remediating diuroncontaminated soils. PLoS ONE 12(8): e0182556. https://doi.org/10.1371/journal.pone.0182556 Editor: Paula V Morais, Universidade de Coimbra, PORTUGAL Received: November 19, 2016 Accepted: July 20, 2017 Published: August 15, 2017 Copyright: © 2017 Wang et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract A diuron-degrading endophyte DP8-1 was isolated from sugarcane root grown in diurontreated soil in the present study. The endophyte was identified as Neurospora intermedia based on the morphological characteristics and sequence analysis. The fermentation parameters including temperature, pH, inoculation size, carbon source, and initial diuron concentration were also investigated for the optimization of degradation efficiency. The results indicated that strain DP8-1 was capable of degrading up to 99% diuron within 3 days under the optimal degrading condition. The study of degradation spectrum indicated that strain DP8-1 could also degrade and utilize fenuron, monuron, metobromuron, isoproturon, chlorbromuron, linuron, and chlortoluron as substrate for strain growth. On basis of liquid chromatography-mass spectrometry analysis for the products of the degradation of diuron, strain DP8-1 metabolized diuron to produce N-(3,4-dichlorophenyl)-urea and N-(3,4-dichlorophenyl)-N-methylurea through sequential N-dealkylations. In a soil bioaugmentation experiment, the inoculation of strain DP8-1 into diuron-treated soil effectively enhanced the disappearance rate of diuron. Data Availability Statement: All sequence data of strain DP8-1 acquired for this study had been deposited in the GenBank under the accession numbers MF362950 to MF362955 (www.ncbi.nlm. nih.gov). Introduction Funding: This work was supported by the Special Fund for Agro-scientific Research in the Public Interest, P.R. China (No. 201203098), National Natural Science Foundation of P.R. China (No. 31460479, 31660524), the Fundamental Research Funds for Guangxi Academy of Agricultural Diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea), a phenylurea herbicide, is widely used as a broad-spectrum herbicide for pre-emergence weed control in a wide variety of crops, especially sugarcane cultures [1]. Diuron is relatively persistent in soil with the mean half-life of approximately 330 days [2], which contaminates surface and ground waters worldwide by runoff [3, 4] and leaching [5, 6]. Diuron is classified as a Priority Hazardous Substance by the PLOS ONE | https://doi.org/10.1371/journal.pone.0182556 August 15, 2017 1 / 18 Biodegradation of diuron and bioremediation of diuron-contaminated soils Sciences (No. 2014YD11) and Foundation of Guangxi Key Laboratory of Biology for Crop Diseases and Insect Pests (No. 2016-ST-1). Competing interests: The authors have declared that no competing interests exist. European Commission (Directive 2000/60/CE) and accordingly has been banned in Europe but remains used in numerous regions of the world. The pollutant of its residues in the environment affects not only terrestrial and aquatic biota but also human health. Additionally, diuron is suspected to be a carcinogenic and genotoxic compound for humans and aquatic organisms [7, 8]. Therefore, the dissipation of this compound from the environment is a central issue. The major route for natural dissipation of diuron from the environment is microbial degradation [9]. The diuron-biodegrading potentials were reported about bacteria such as Arthrobacter sp. N2 [10, 11], Acinetobacter johnsonii [12], Streptomycete strains [13], Micrococcus sp. PS-1 [14, 15], and Bacillus, Vagococcus, and Burkholderia spp. [16] isolated from soil samples. Diuron-degrading bacteria identified as Pseudomonas sp. and Stenotrophomonas sp. were isolated from lotic surface water that has been sensitized to diuron exposure for more than 10 years [17]. The degradation potentials for diuron of five soil fungus Mortierella strains were compared [18]. The white-rot fungus Phanerochaete chrysosporium was reported for its capacity to degrade diuron in liquid stationary cultures [1]. Sørensen et al. examined the degradation and mineralization of diuron at low concentrations by Sphingomonas sp. SRS2 from soil samples in a British agricultural field [19]. So far, the majority of studies on the biodegradation of diuron have focused on microbes isolated from soil, sludge, sediment and water samples in various diuron exposed environments. At present, fewer studies have reported about the biodegradation of herbicides by using endophytic microbes that reside in the internal tissues of plants without causing apparent negative symptoms of infection. It was demonstrated that endophytes play a key role in host plant adaptation in polluted environment [20]. Herbicide-degrading endophytes could be isolated from plants grown in herbicide-treated areas. It was reported that endophytic rhizobacteria for the degradation of simazine were isolated from the roots of corn plants and the nodules of soybean plants [21]. A study isolated endophytic bacteria Pseudomonas oryzihabitans and Burkholderia gladioliwhich from soybean grown in soil treated with glyphosate herbicide [22]. Recently, an endophytic quinclorac-degrading bacterium Bacillus megaterium Q3 was isolated from the root of tobacco grown in quinclorac-contaminated soil [23]. Up to now, it has not been reported endophytic microorganisms able to degrade diuron. In the present paper, a diuron-degrading endophytic fungus DP8-1 was isolated from the root of sugarcane grown in a diuron-treated field. The morphological characteristics and sequence analysis of this endophyte was investigated to identify it as Neurospora intermedia. The effect fa (...truncated)